SummaryConverging studies from psychophysics in humans to single-cell recordings in monkeys and rodents indicate that most important cognitive processes depend on both feed-forward and feedback information interacting in the brain. Intriguingly, feedback to early cortical processing stages appears to play a causal role in these processes. Despite the central nature of this fact to understanding brain cognition, there is still no mechanistic explanation as to how this information could be so pivotal and what events take place that might be decisive. In this research program, we will test the hypothesis that the extraordinary performance of the cortex derives from an associative mechanism built into the basic neuronal unit: the pyramidal cell. The hypothesis is based on two important facts: (1) feedback information is conveyed predominantly to layer 1 and (2) the apical tuft dendrites that are the major recipient of this feedback information are highly electrogenic.
The research program is divided in to several workpackages to systematically investigate the hypothesis at every level. As a whole, we will investigate the causal link between intrinsic cellular activity and behaviour. To do this we will use eletrophysiological and optical techniques to record and influence cell the intrinsic properties of cells (in particular dendritic activity) in vivo and in vitro in rodents. In vivo experiments will have a specific focus on context driven behaviour and in vitro experiments on the impact of long-range (feedback-carrying) fibers on cell activity. The study will also focus on synaptic plasticity at the interface of feedback information and dendritic electrogenesis, namely synapses on to the tuft dendrite of pyramidal neurons. The proposed program will not only address a long-standing and important hypothesis but also provide a transformational contribution towards understanding the operation of the cerebral cortex.

Converging studies from psychophysics in humans to single-cell recordings in monkeys and rodents indicate that most important cognitive processes depend on both feed-forward and feedback information interacting in the brain. Intriguingly, feedback to early cortical processing stages appears to play a causal role in these processes. Despite the central nature of this fact to understanding brain cognition, there is still no mechanistic explanation as to how this information could be so pivotal and what events take place that might be decisive. In this research program, we will test the hypothesis that the extraordinary performance of the cortex derives from an associative mechanism built into the basic neuronal unit: the pyramidal cell. The hypothesis is based on two important facts: (1) feedback information is conveyed predominantly to layer 1 and (2) the apical tuft dendrites that are the major recipient of this feedback information are highly electrogenic.
The research program is divided in to several workpackages to systematically investigate the hypothesis at every level. As a whole, we will investigate the causal link between intrinsic cellular activity and behaviour. To do this we will use eletrophysiological and optical techniques to record and influence cell the intrinsic properties of cells (in particular dendritic activity) in vivo and in vitro in rodents. In vivo experiments will have a specific focus on context driven behaviour and in vitro experiments on the impact of long-range (feedback-carrying) fibers on cell activity. The study will also focus on synaptic plasticity at the interface of feedback information and dendritic electrogenesis, namely synapses on to the tuft dendrite of pyramidal neurons. The proposed program will not only address a long-standing and important hypothesis but also provide a transformational contribution towards understanding the operation of the cerebral cortex.

SummaryThe goal of this project is to demonstrate that novel aspects of the molecular basis of Darwinian adaptation can be discovered if the polygenic basis of adaptation is taken into account. This project will use the genome-wide distribution of cis-regulatory variants to discover the molecular pathways that are optimized during adaptation via accumulation of small effect mutations. Current approaches include scans for outlier genes with strong population genetics signatures of selection, or large effect QTL associating with fitness. They can only reveal a small subset of the molecular changes recruited along adaptive paths. Here, instead, the distribution of small effect mutations will be used to make inferences on the targets of polygenic adaptation across divergent populations in each of the two closely related species, A. thaliana and A. lyrata. These species are both found at diverse latitudes and show sign of local adaptation to climatic differences. Mutations affecting cis-regulation will be identified in leaves of plants exposed to various temperature regimes triggering phenotypic responses of adaptive relevance. Their distribution in clusters of functionally connected genes will be quantified. The phylogeographic differences in the distribution of the mutations will be used to disentangle neutral from adaptive clusters of functionally connected genes in each of the two species. This project will identify the molecular pathways subjected collectively to natural selection and provide a completely novel view on adaptive landscapes. It will further examine whether local adaptation occurs by convergent evolution of molecular systems in plants. This approach has the potential to find broad applications in ecology and agriculture.

The goal of this project is to demonstrate that novel aspects of the molecular basis of Darwinian adaptation can be discovered if the polygenic basis of adaptation is taken into account. This project will use the genome-wide distribution of cis-regulatory variants to discover the molecular pathways that are optimized during adaptation via accumulation of small effect mutations. Current approaches include scans for outlier genes with strong population genetics signatures of selection, or large effect QTL associating with fitness. They can only reveal a small subset of the molecular changes recruited along adaptive paths. Here, instead, the distribution of small effect mutations will be used to make inferences on the targets of polygenic adaptation across divergent populations in each of the two closely related species, A. thaliana and A. lyrata. These species are both found at diverse latitudes and show sign of local adaptation to climatic differences. Mutations affecting cis-regulation will be identified in leaves of plants exposed to various temperature regimes triggering phenotypic responses of adaptive relevance. Their distribution in clusters of functionally connected genes will be quantified. The phylogeographic differences in the distribution of the mutations will be used to disentangle neutral from adaptive clusters of functionally connected genes in each of the two species. This project will identify the molecular pathways subjected collectively to natural selection and provide a completely novel view on adaptive landscapes. It will further examine whether local adaptation occurs by convergent evolution of molecular systems in plants. This approach has the potential to find broad applications in ecology and agriculture.

SummaryEndothelial cells comprise the inner cellular cover of the vasculature, which delivers metabolites and oxygen to the tissue. Dysfunction of endothelial cells as it occurs during aging or metabolic syndromes can result in atherosclerosis, which can lead to myocardial infarction or stroke, whereas pathological angiogenesis contributes to tumor growth and diabetic retinopathy. Thus, endothelial cells play central roles in pathophysiological processes of many diseases including cardiovascular diseases and cancer. Many studies explored the regulation of endothelial cell functions by growth factors, but the impact of epigenetic mechanisms and particularly the role of novel non-coding RNAs is largely unknown. More than 70 % of the human genome encodes for non-coding RNAs (ncRNAs) and increasing evidence suggests that a significant portion of these ncRNAs are functionally active as RNA molecules. Angiolnc aims to explore the function of long ncRNAs (lncRNAs) and particular circular RNAs (circRNAs) in the endothelium. LncRNAs comprise a heterogenic class of RNAs with a length of > 200 nucleotides and circRNAs are generated by back splicing.
Angiolnc is based on the discovery of novel endothelial hypoxia-regulated lncRNAs and circRNAs by next generation sequencing. To begin to understand the potential functions of lncRNAs in the endothelium, we will study two lncRNAs, named Angiolnc1 und Angiolnc2, as prototypical examples of endothelial cell-enriched lncRNAs that are regulated by oxygen levels. We will further dissect the epigenetic mechanisms, by which these lncRNAs regulate endothelial cell function. In the second part of the application, we will determine the regulation and function of circRNAs, which may act as molecular sponges in the cytoplasm. Finally, we will study the function of identified lncRNAs and circRNAs in mouse models and measure their expression in human specimens in order to determine their role as therapeutic targets or diagnostic tools.

Endothelial cells comprise the inner cellular cover of the vasculature, which delivers metabolites and oxygen to the tissue. Dysfunction of endothelial cells as it occurs during aging or metabolic syndromes can result in atherosclerosis, which can lead to myocardial infarction or stroke, whereas pathological angiogenesis contributes to tumor growth and diabetic retinopathy. Thus, endothelial cells play central roles in pathophysiological processes of many diseases including cardiovascular diseases and cancer. Many studies explored the regulation of endothelial cell functions by growth factors, but the impact of epigenetic mechanisms and particularly the role of novel non-coding RNAs is largely unknown. More than 70 % of the human genome encodes for non-coding RNAs (ncRNAs) and increasing evidence suggests that a significant portion of these ncRNAs are functionally active as RNA molecules. Angiolnc aims to explore the function of long ncRNAs (lncRNAs) and particular circular RNAs (circRNAs) in the endothelium. LncRNAs comprise a heterogenic class of RNAs with a length of > 200 nucleotides and circRNAs are generated by back splicing.
Angiolnc is based on the discovery of novel endothelial hypoxia-regulated lncRNAs and circRNAs by next generation sequencing. To begin to understand the potential functions of lncRNAs in the endothelium, we will study two lncRNAs, named Angiolnc1 und Angiolnc2, as prototypical examples of endothelial cell-enriched lncRNAs that are regulated by oxygen levels. We will further dissect the epigenetic mechanisms, by which these lncRNAs regulate endothelial cell function. In the second part of the application, we will determine the regulation and function of circRNAs, which may act as molecular sponges in the cytoplasm. Finally, we will study the function of identified lncRNAs and circRNAs in mouse models and measure their expression in human specimens in order to determine their role as therapeutic targets or diagnostic tools.

SummaryDeregulated apoptotic signaling in hematopoietic stem and progenitor cells (HSPCs) strongly contributes to the pathogenesis and phenotypes of congenital bone marrow failure and myelodysplastic syndromes (MDS) and their progression to acute myeloid leukemia (AML). HSPCs are highly susceptible to apoptosis during bone marrow failure and early MDS, but AML evolution selects for apoptosis resistance. Little is known about the main apoptotic players and their regulators. ApoptoMDS will investigate the impact of apoptotic deregulation for pathogenesis, correlate apoptotic susceptibility with the kinetics of disease progression and characterize the mechanism by which apoptotic susceptibility turns into resistance. ApoptoMDS will draw on a large collection of patient-derived samples and genetically engineered mouse models to investigate disease progression in serially transplanted and xenotransplanted mice. How activated DNA damage checkpoint signaling contributes to syndrome phenotypes and HSPC hypersusceptibility to apoptosis will be assessed. Checkpoint activation confers a competitive disadvantage, and HSPCs undergoing malignant transformation are under high selective pressure to inactivate it. Checkpoint abrogation mitigates the hematological phenotype, but increases the risk of AML evolution. ApoptoMDS aims to analyze if inhibiting apoptosis in HSPCs from bone marrow failure and early-stage MDS can overcome the dilemma of checkpoint abrogation. Whether inhibiting apoptosis is sufficient to improve HSPC function will be tested on several levels and validated in patient-derived samples. How inhibiting apoptosis in the presence of functional checkpoint signaling influences malignant transformation kinetics will be assessed. If, as hypothesized, inhibiting apoptosis both mitigates hematological symptoms and delays AML evolution, ApoptoMDS will pave the way for novel therapeutic approaches to expand the less severe symptomatic period for patients with these syndromes.

Deregulated apoptotic signaling in hematopoietic stem and progenitor cells (HSPCs) strongly contributes to the pathogenesis and phenotypes of congenital bone marrow failure and myelodysplastic syndromes (MDS) and their progression to acute myeloid leukemia (AML). HSPCs are highly susceptible to apoptosis during bone marrow failure and early MDS, but AML evolution selects for apoptosis resistance. Little is known about the main apoptotic players and their regulators. ApoptoMDS will investigate the impact of apoptotic deregulation for pathogenesis, correlate apoptotic susceptibility with the kinetics of disease progression and characterize the mechanism by which apoptotic susceptibility turns into resistance. ApoptoMDS will draw on a large collection of patient-derived samples and genetically engineered mouse models to investigate disease progression in serially transplanted and xenotransplanted mice. How activated DNA damage checkpoint signaling contributes to syndrome phenotypes and HSPC hypersusceptibility to apoptosis will be assessed. Checkpoint activation confers a competitive disadvantage, and HSPCs undergoing malignant transformation are under high selective pressure to inactivate it. Checkpoint abrogation mitigates the hematological phenotype, but increases the risk of AML evolution. ApoptoMDS aims to analyze if inhibiting apoptosis in HSPCs from bone marrow failure and early-stage MDS can overcome the dilemma of checkpoint abrogation. Whether inhibiting apoptosis is sufficient to improve HSPC function will be tested on several levels and validated in patient-derived samples. How inhibiting apoptosis in the presence of functional checkpoint signaling influences malignant transformation kinetics will be assessed. If, as hypothesized, inhibiting apoptosis both mitigates hematological symptoms and delays AML evolution, ApoptoMDS will pave the way for novel therapeutic approaches to expand the less severe symptomatic period for patients with these syndromes.

Max ERC Funding

1 372 525 €

Duration

Start date: 2015-06-01, End date: 2020-05-31

Project acronymAUROMYC

ProjectN-Myc and Aurora A: From Protein Stability to Chromosome Topology N-Myc and Aurora A: From Protein Stability to Chromosome Topology Myc and Aurora A: From Protein Stability to Chromosome Topology

Researcher (PI)Martin Eilers

Host Institution (HI)JULIUS-MAXIMILIANS-UNIVERSITAT WURZBURG

Call DetailsAdvanced Grant (AdG), LS4, ERC-2014-ADG

SummaryThere is an intense interest in the function of human Myc proteins that stems from their pervasive role in the genesis of human tumors. A large body of evidence has established that expression levels of one of three closely related Myc proteins are enhanced in the majority of all human tumors and that multiple tumor entities depend on elevated Myc function, arguing that targeting Myc will have significant therapeutic efficacy. This hope awaits clinical confirmation, since the strategies that are currently under investigation to target Myc function or expression have yet to enter the clinic. Myc proteins are global regulators of transcription, but their mechanism of action is poorly understood.
Myc proteins are highly unstable in normal cells and rapidly turned over by the ubiquitin/proteasome system. In contrast, they are stabilized in tumor cells. Work by us and by others has shown that stabilization of Myc is required for tumorigenesis and has identified strategies to destabilize Myc for tumor therapy. This work has also led to the surprising observation that the N-Myc protein, which drives neuroendocrine tumorigenesis, is stabilized by association with the Aurora-A kinase and that clinically available Aurora-A inhibitors can dissociate the complex and destabilize N-Myc. Aurora-A has not previously been implicated in transcription, prompting us to use protein crystallography, proteomics and shRNA screening to understand its interaction with N-Myc. We have now identified a novel protein complex of N-Myc and Aurora-A that provides an unexpected and potentially groundbreaking insight into Myc function. We have also solved the crystal structure of the N-Myc/Aurora-A complex. Collectively, both findings open new strategies to target Myc function for tumor therapy.

There is an intense interest in the function of human Myc proteins that stems from their pervasive role in the genesis of human tumors. A large body of evidence has established that expression levels of one of three closely related Myc proteins are enhanced in the majority of all human tumors and that multiple tumor entities depend on elevated Myc function, arguing that targeting Myc will have significant therapeutic efficacy. This hope awaits clinical confirmation, since the strategies that are currently under investigation to target Myc function or expression have yet to enter the clinic. Myc proteins are global regulators of transcription, but their mechanism of action is poorly understood.
Myc proteins are highly unstable in normal cells and rapidly turned over by the ubiquitin/proteasome system. In contrast, they are stabilized in tumor cells. Work by us and by others has shown that stabilization of Myc is required for tumorigenesis and has identified strategies to destabilize Myc for tumor therapy. This work has also led to the surprising observation that the N-Myc protein, which drives neuroendocrine tumorigenesis, is stabilized by association with the Aurora-A kinase and that clinically available Aurora-A inhibitors can dissociate the complex and destabilize N-Myc. Aurora-A has not previously been implicated in transcription, prompting us to use protein crystallography, proteomics and shRNA screening to understand its interaction with N-Myc. We have now identified a novel protein complex of N-Myc and Aurora-A that provides an unexpected and potentially groundbreaking insight into Myc function. We have also solved the crystal structure of the N-Myc/Aurora-A complex. Collectively, both findings open new strategies to target Myc function for tumor therapy.

SummaryI propose to study how eukaryotic cells generate autophagosomes, organelles bounded by a double membrane. These are formed during autophagy and mediate the degradation of cytoplasmic substances within the lysosomal compartment. Autophagy thereby protects the organism from pathological conditions such as neurodegeneration, cancer and infections. Many core factors required for autophagosome formation have been identified but the order in which they act and their mode of action is still unclear. We will use a combination of biochemical and cell biological approaches to elucidate the choreography and mechanism of these core factors. In particular, we will focus on selective autophagy and determine how the autophagic machinery generates an autophagosome that selectively contains the cargo.
To this end we will focus on the cytoplasm-to-vacuole-targeting pathway in S. cerevisiae that mediates the constitutive delivery of the prApe1 enzyme into the vacuole. We will use cargo mimetics or prApe1 complexes in combination with purified autophagy proteins and vesicles to reconstitute the process and so determine which factors are both necessary and sufficient for autophagosome formation, as well as elucidating their mechanism of action.
In parallel we will study selective autophagosome formation in human cells. This will reveal common principles and special adaptations. In particular, we will use cell lysates from genome-edited cells in combination with purified autophagy proteins to reconstitute selective autophagosome formation around ubiquitin-positive cargo material. The insights and hypotheses obtained from these reconstituted systems will be validated using cell biological approaches.
Taken together, our experiments will allow us to delineate the major steps of autophagosome formation during selective autophagy. Our results will yield detailed insights into how cells form and shape organelles in a de novo manner, which is major question in cell- and developmental biology.

I propose to study how eukaryotic cells generate autophagosomes, organelles bounded by a double membrane. These are formed during autophagy and mediate the degradation of cytoplasmic substances within the lysosomal compartment. Autophagy thereby protects the organism from pathological conditions such as neurodegeneration, cancer and infections. Many core factors required for autophagosome formation have been identified but the order in which they act and their mode of action is still unclear. We will use a combination of biochemical and cell biological approaches to elucidate the choreography and mechanism of these core factors. In particular, we will focus on selective autophagy and determine how the autophagic machinery generates an autophagosome that selectively contains the cargo.
To this end we will focus on the cytoplasm-to-vacuole-targeting pathway in S. cerevisiae that mediates the constitutive delivery of the prApe1 enzyme into the vacuole. We will use cargo mimetics or prApe1 complexes in combination with purified autophagy proteins and vesicles to reconstitute the process and so determine which factors are both necessary and sufficient for autophagosome formation, as well as elucidating their mechanism of action.
In parallel we will study selective autophagosome formation in human cells. This will reveal common principles and special adaptations. In particular, we will use cell lysates from genome-edited cells in combination with purified autophagy proteins to reconstitute selective autophagosome formation around ubiquitin-positive cargo material. The insights and hypotheses obtained from these reconstituted systems will be validated using cell biological approaches.
Taken together, our experiments will allow us to delineate the major steps of autophagosome formation during selective autophagy. Our results will yield detailed insights into how cells form and shape organelles in a de novo manner, which is major question in cell- and developmental biology.

Max ERC Funding

1 999 640 €

Duration

Start date: 2016-03-01, End date: 2021-02-28

Project acronymAuxinER

ProjectMechanisms of Auxin-dependent Signaling in the Endoplasmic Reticulum

Researcher (PI)Jürgen Kleine-Vehn

Host Institution (HI)UNIVERSITAET FUER BODENKULTUR WIEN

Call DetailsStarting Grant (StG), LS3, ERC-2014-STG

SummaryThe phytohormone auxin has profound importance for plant development. The extracellular AUXIN BINDING PROTEIN1 (ABP1) and the nuclear AUXIN F-BOX PROTEINs (TIR1/AFBs) auxin receptors perceive fast, non-genomic and slow, genomic auxin responses, respectively. Despite the fact that ABP1 mainly localizes to the endoplasmic reticulum (ER), until now it has been proposed to be active only in the extracellular matrix (reviewed in Sauer and Kleine-Vehn, 2011). Just recently, ABP1 function was also linked to genomic responses, modulating TIR1/AFB-dependent processes (Tromas et al., 2013). Intriguingly, the genomic effect of ABP1 appears to be at least partially independent of the endogenous auxin indole 3-acetic acid (IAA) (Paque et al., 2014).
In this proposal my main research objective is to unravel the importance of the ER for genomic auxin responses. The PIN-LIKES (PILS) putative carriers for auxinic compounds also localize to the ER and determine the cellular sensitivity to auxin. PILS5 gain-of-function reduces canonical auxin signaling (Barbez et al., 2012) and phenocopies abp1 knock down lines (Barbez et al., 2012, Paque et al., 2014). Accordingly, a PILS-dependent substrate could be a negative regulator of ABP1 function in the ER. Based on our unpublished data, an IAA metabolite could play a role in ABP1-dependent processes in the ER, possibly providing feedback on the canonical nuclear IAA-signaling.
I hypothesize that the genomic auxin response may be an integration of auxin- and auxin-metabolite-dependent nuclear and ER localized signaling, respectively. This proposed project aims to characterize a novel auxin-signaling paradigm in plants. We will employ state of the art interdisciplinary (biochemical, biophysical, computational modeling, molecular, and genetic) methods to assess the projected research. The identification of the proposed auxin conjugate-dependent signal could have far reaching plant developmental and biotechnological importance.

The phytohormone auxin has profound importance for plant development. The extracellular AUXIN BINDING PROTEIN1 (ABP1) and the nuclear AUXIN F-BOX PROTEINs (TIR1/AFBs) auxin receptors perceive fast, non-genomic and slow, genomic auxin responses, respectively. Despite the fact that ABP1 mainly localizes to the endoplasmic reticulum (ER), until now it has been proposed to be active only in the extracellular matrix (reviewed in Sauer and Kleine-Vehn, 2011). Just recently, ABP1 function was also linked to genomic responses, modulating TIR1/AFB-dependent processes (Tromas et al., 2013). Intriguingly, the genomic effect of ABP1 appears to be at least partially independent of the endogenous auxin indole 3-acetic acid (IAA) (Paque et al., 2014).
In this proposal my main research objective is to unravel the importance of the ER for genomic auxin responses. The PIN-LIKES (PILS) putative carriers for auxinic compounds also localize to the ER and determine the cellular sensitivity to auxin. PILS5 gain-of-function reduces canonical auxin signaling (Barbez et al., 2012) and phenocopies abp1 knock down lines (Barbez et al., 2012, Paque et al., 2014). Accordingly, a PILS-dependent substrate could be a negative regulator of ABP1 function in the ER. Based on our unpublished data, an IAA metabolite could play a role in ABP1-dependent processes in the ER, possibly providing feedback on the canonical nuclear IAA-signaling.
I hypothesize that the genomic auxin response may be an integration of auxin- and auxin-metabolite-dependent nuclear and ER localized signaling, respectively. This proposed project aims to characterize a novel auxin-signaling paradigm in plants. We will employ state of the art interdisciplinary (biochemical, biophysical, computational modeling, molecular, and genetic) methods to assess the projected research. The identification of the proposed auxin conjugate-dependent signal could have far reaching plant developmental and biotechnological importance.

Max ERC Funding

1 441 125 €

Duration

Start date: 2015-06-01, End date: 2020-11-30

Project acronymbi-BLOCK

ProjectBuilding and bypassing plant polyspermy blocks

Researcher (PI)Rita Helene Groß-Hardt

Host Institution (HI)UNIVERSITAET BREMEN

Call DetailsConsolidator Grant (CoG), LS3, ERC-2014-CoG

SummaryThe ultimate goal for the survival of all species on earth is to reproduce. This uncompromising principle has triggered the evolution of numerous adaptations. One strategy commonly employed by sexually reproducing eukaryotes is the production of tremendous amounts of sperm to maximize the likelihood of an egg becoming fertilised. High sperm to egg ratios are, however, associated with an increased risk of supernumerary sperm fusion. This so-called polyspermy is lethal in many organisms. Accordingly, eukaryotes have evolved polyspermy barriers, which are implemented at different levels in the reproductive process. Flowering plants tightly control the number of sperm-transporting pollen tubes approaching a single ovule by a so-called pollen tube block. We have recently shown that the pollen tube block is relaxed in ethylene hyposensitive plants. Capitalizing on these results, this project aims at identifying and characterising the molecular mechanisms underlying plant polyspermy barriers.

The ultimate goal for the survival of all species on earth is to reproduce. This uncompromising principle has triggered the evolution of numerous adaptations. One strategy commonly employed by sexually reproducing eukaryotes is the production of tremendous amounts of sperm to maximize the likelihood of an egg becoming fertilised. High sperm to egg ratios are, however, associated with an increased risk of supernumerary sperm fusion. This so-called polyspermy is lethal in many organisms. Accordingly, eukaryotes have evolved polyspermy barriers, which are implemented at different levels in the reproductive process. Flowering plants tightly control the number of sperm-transporting pollen tubes approaching a single ovule by a so-called pollen tube block. We have recently shown that the pollen tube block is relaxed in ethylene hyposensitive plants. Capitalizing on these results, this project aims at identifying and characterising the molecular mechanisms underlying plant polyspermy barriers.

SummarySurfactant Protein B (SP-B) deficiency and Cystic Fibrosis (CF) are severe, fatal inherited diseases affecting the lungs of ten thousands of people, for which there is currently no available cure. Although gene therapy is a promising therapeutic approach, various technical problems, including numerous physical and immune-mediated barriers, have prevented successful application to date. My recent studies were the first to demonstrate the life-saving efficacy of repeated pulmonary delivery of chemically modified messenger RNA (mRNA) in a mouse model of congenital SP-B deficiency. By incorporating balanced amounts of modified nucleotides to mimic endogenous transcripts, I developed a safe and therapeutically efficient vehicle for lung transfection that eliminates the risk of genomic integration commonly associated with DNA-based vectors. I also assessed the delivery of mRNA-encoded site-specific nucleases to the lung to facilitate targeted gene correction of the underlying disease-causing mutations. In comprehensive studies, we show that a single application of nucleases encoded by nucleotide-modified RNA (nec-mRNA) can generate in vivo correction of terminally differentiated alveolar type II cells, which more than quadrupled the life span of SP-B deficient mice. Together with my working group, I aim to further develop this technology to enhance the efficiency and safety of nec-mRNA-mediated in vivo lung stem cell targeting, providing an ultimate cure by permanent correction. Specifically, we will test this approach in humanized mouse models of SP-B deficiency and CF. Developing and genetically engineering humanized models in vivo will be a critical step towards the safe translation of mRNA based nuclease technology to the clinic. With my competitive edge in lung-transfection technology and strong data, I feel that my group is uniquely suited to achieve these goals and to make a highly valuable contribution to the development of an efficient treatment.

Surfactant Protein B (SP-B) deficiency and Cystic Fibrosis (CF) are severe, fatal inherited diseases affecting the lungs of ten thousands of people, for which there is currently no available cure. Although gene therapy is a promising therapeutic approach, various technical problems, including numerous physical and immune-mediated barriers, have prevented successful application to date. My recent studies were the first to demonstrate the life-saving efficacy of repeated pulmonary delivery of chemically modified messenger RNA (mRNA) in a mouse model of congenital SP-B deficiency. By incorporating balanced amounts of modified nucleotides to mimic endogenous transcripts, I developed a safe and therapeutically efficient vehicle for lung transfection that eliminates the risk of genomic integration commonly associated with DNA-based vectors. I also assessed the delivery of mRNA-encoded site-specific nucleases to the lung to facilitate targeted gene correction of the underlying disease-causing mutations. In comprehensive studies, we show that a single application of nucleases encoded by nucleotide-modified RNA (nec-mRNA) can generate in vivo correction of terminally differentiated alveolar type II cells, which more than quadrupled the life span of SP-B deficient mice. Together with my working group, I aim to further develop this technology to enhance the efficiency and safety of nec-mRNA-mediated in vivo lung stem cell targeting, providing an ultimate cure by permanent correction. Specifically, we will test this approach in humanized mouse models of SP-B deficiency and CF. Developing and genetically engineering humanized models in vivo will be a critical step towards the safe translation of mRNA based nuclease technology to the clinic. With my competitive edge in lung-transfection technology and strong data, I feel that my group is uniquely suited to achieve these goals and to make a highly valuable contribution to the development of an efficient treatment.

Max ERC Funding

1 497 125 €

Duration

Start date: 2015-04-01, End date: 2020-03-31

Project acronymCancerHetero

ProjectDissection of tumor heterogeneity in vivo

Researcher (PI)Haikun Liu

Host Institution (HI)DEUTSCHES KREBSFORSCHUNGSZENTRUM HEIDELBERG

Call DetailsConsolidator Grant (CoG), LS2, ERC-2014-CoG

SummaryIt is now widely accepted that tumors are composed of heterogeneous population of cells, which contribute
to many aspects of treatment resistance observed in clinic. Despite the acknowledgment of the tumor cell
heterogeneity, little evidence was shown about complexity and dynamics of this heterogeneity in vivo,
mainly because of lacking flexible genetic tools which allow sophisticated analysis in primary tumors. We
recently developed a very efficient mouse somatic brain tumor model which have a full penetrance of high
grade glioma development. Combination of this model with several transgenic mouse lines allow us to
isolate and track different population of cells in primary tumors, most importantly, we also confirmed that
this can be done on single cell level. Here I propose to use this set of valuable genetic tools to dissect the
cellular heterogeneity in mouse gliomas. First we will perform several single cell lineage tracing experiment
to demonstrate the contribution of brain tumor stem cell, tumor progenitors as well as the relatively
differentiated cells, which will provide a complete data sets of clonal dynamics of different tumor cell types.
Second we will further perform this tracing experiment with the presence of conventional chemotherapy.
Third we will perform single cell RNA sequencing experiment to capture the molecular signature, which
determines the cellular heterogeneity, discovered by single cell tracing. This result will be further validated
by analysis of this molecular signatures in human primary tumors. We will also use our established in vivo
target validation approach to manipulate the candidate molecular regulators to establish the functional
correlation between molecular signature and phenotypic heterogeneity. This project will greatly improve our
understanding of tumor heterogeneity, and possibly provide novel approaches and strategies of targeting
human glioblastomas.

It is now widely accepted that tumors are composed of heterogeneous population of cells, which contribute
to many aspects of treatment resistance observed in clinic. Despite the acknowledgment of the tumor cell
heterogeneity, little evidence was shown about complexity and dynamics of this heterogeneity in vivo,
mainly because of lacking flexible genetic tools which allow sophisticated analysis in primary tumors. We
recently developed a very efficient mouse somatic brain tumor model which have a full penetrance of high
grade glioma development. Combination of this model with several transgenic mouse lines allow us to
isolate and track different population of cells in primary tumors, most importantly, we also confirmed that
this can be done on single cell level. Here I propose to use this set of valuable genetic tools to dissect the
cellular heterogeneity in mouse gliomas. First we will perform several single cell lineage tracing experiment
to demonstrate the contribution of brain tumor stem cell, tumor progenitors as well as the relatively
differentiated cells, which will provide a complete data sets of clonal dynamics of different tumor cell types.
Second we will further perform this tracing experiment with the presence of conventional chemotherapy.
Third we will perform single cell RNA sequencing experiment to capture the molecular signature, which
determines the cellular heterogeneity, discovered by single cell tracing. This result will be further validated
by analysis of this molecular signatures in human primary tumors. We will also use our established in vivo
target validation approach to manipulate the candidate molecular regulators to establish the functional
correlation between molecular signature and phenotypic heterogeneity. This project will greatly improve our
understanding of tumor heterogeneity, and possibly provide novel approaches and strategies of targeting
human glioblastomas.